This invention concerns a contact free tridimensional process for measuring the outer shape of an object, specifically a human foot, with a view to making made-to-measure footwear, whether or not of the orthopaedic variety.
This measurement process can also be extended to all tridimensional objects.
This invention also concerns the measurement equipment used for the process.
The various stages of made-to-measure show production consist in measuring the foot, producing, on the basis of measurement recorded, a last currently and hereinafter designated "last", measuring this last and, on the basis of measurements recorded, cutting out the various parts designated "patterns" from some material such as leather; then finally assembling these sundry parts primarily by means of stitching and bonding, the last being used as a support.
The first phase of this invention process, therefore, applies to the production of a made-to-measure shoe, that is to say a shoes which is made to fit the foot.
One known measurement procedure consists in manually measuring the foot using a tape. This system presents a number of drawbacks. Indeed, there is contact between the tape and the foot; there will be variations in tape tension and positioning; these all introduce variables into the measurements, the number of which are limited to a few peripheral and contour records (between 5 and 10), and, finally, it is impossible to obtain accurate measurements in space using this system. Thus the tridimensional form data can be regarded as virtually nil since only projections and perimeters are measured.
Another current contact-free process consists in measuring the foot using a "cross hatching" technique or a single laser plane associated with a photographic picture, which, when connected to a computer, define three coordinates for each measurement point. This digitization measurement technique is more accurate than the manual measurement system but the foot is measured "without load", i.e. it does not bear on the ground. This "no-load" system means that the sole of the foot can be measured directly. However, it presents a major drawback since the shape of the foot will alter when it is under load (when the person is standing) and "no-load" measurements will not apply to the "loaded" foot configuration.
Therefore, this system furnishes distorted data and, further, requires a much greater number of reference points in order to measure the sole and the arch of the foot.